a) Field of the Invention
The present invention relates to a negative resistance line using an active element having at least three terminals.
b) Description of the Related Art
Ultra high speed pulse transmission techniques in the order of 100 G bits/sec are being developed in the age of high capacity and high speed communications. In order to transmit a pulse at such high speed, an ultra broadband amplifier is required which has a gain-bandwidth product in the order of tera Hz and is terminated at 50.OMEGA. without power reflection. In order to meet such requirements, a distributed progressive wave amplifier using high performance high electron mobility transistors (HEMT) are being developed. A gain-bandwidth product of 150 GHz can be realized by a distributed progressive wave amplifier using HEMTs.
Although the gain-bandwidth product of 150 GHz can be obtained by a distributed progressive amplifier using HEMTs, its power gain is smaller than a performance expected from a cutoff frequency f.sub.t of HEMT and distributed constant effects. The reasons of the lower performance than expected may be no incorporation of distributed constants into each HEMT, a limit of the number of cascade connections, a limit of fine segmentation of a line length, a mutual conductance G.sub.m lowered by a phase matching gate stub line, and the like.